[Linuxsampler-devel] GigaStudio LFO compatibility

[Christian S. <sch...@li...>]

Hi all,

I was reviewing our gig engine's LFO code and noticed that their behaviour 
does not match with GigaStudio's original LFO behaviour. So I planned to 
change that:

1. Our gig engine is using triangle LFOs whereas it looks like GigaStudio 
   actually had sine LFOs. So my plan is to make sine to become default and 
   make triangle available as option instead (as part of a new gig file format 
   extension). Looks like GSt only ever had one function type (sine) for LFOs.

2. Start value of unsigned LFOs (which are amplitude LFO and filter cutoff LFO 
   in the gig engine): I see that our implementation of those 2 (unsigned) 	
	LFOs start with wrong initial values; the very 1st rendered sample is 0 and 
   then the function jumps to the middle of the value range and continues from
   there. That initial jump is certainly a bug that should be fixed. But what 
   about the actual start point; does anybody know whether GSt starts with
	a) zero, or b) mid value range, or c) max. value on those 2 LFOs (amp LFO & 
   filter cutoff LFO)?

A start phase option for our LFOs (as format extension) might make sense as 
well BTW.

CU
Christian